The band befriended Mandela years ago, according to their website. Watching clips of the film, which stars Idris Elba (The Wire, Luther) and Naomie Harris (Skyfall, 28 Days Later . . .), inspired them to write the song.

"When I asked them to consider writing a song for Mandela: Long Walk to Freedom, it was the fastest 'yes' I have ever received," movie producer Harvey Weinstein has said. "The band saw various cuts of the film over the summer and worked diligently to write a song that truly reflects Nelson Mandela. I think they did a brilliant job honoring the man and the leader they have known for over 20 years."

Meanwhile, the group is eyeing a possible April release for its as-yet-untitled new album. According to a recent report, U2 are in talks with "brand partners" for a Super Bowl ad that would announce the LP.

Reports emerged over the summer that the group was working on the LP in New York, where they had been recording with producer Danger Mouse. Last month, bassist Adam Clayton said that the band was "still at it." "I think it's a bit of a return to U2 of old, but with the maturity, if you like, of the U2 of the last 10 years," he said at the time. "It's a combination of those two things and it's a really interesting hybrid. We're in the studio. We're trying to get these 12 songs absolutely right and get them finished by the end of November, and then we can kind of enjoy Christmas."